Non-cyanide alkaline composition for dissolving non-ferrous metals

ABSTRACT

Non-cyanide alkaline aqueous solutions for stripping non-ferrous metals, especially copper, from ferrous metal such as, for example, steel. The stripper solution comprises a water-soluble nitrate, a water-soluble compound of the formula   wherein R represents a valence bond, -CH2-x WHEREIN X IS AN INTEGER OF 1 TO 2,   WHEREIN Y IS AN INTEGER OF 1 TO 2, OR   and M is a compatible, hydrophilic, i.e. water-loving or watersolibilizing, cation, a water-soluble persulfate, a water-soluble urea compound, and ammonium hydroxide. Brass, cadmium and zinc can also be stripped from steel by the stripper or dissolving solutions herein.

United States Patent 1 1 Fadgen, Jr.

1 1 NON-CYANIDE ALKALINE COMPOSITION FOR DlSSOLVlNG NON-FERROUS METALS 1175] lnventor: Earl J. Fadgen, Jr., Clinton, Conn.

173] Assignee: Enthone, Incorporated, West Haven,

Conn.

221 Filed: Aug. 27, 1973 211 Appl. No.: 392,169

l 56] References Cited UNITED STATES PATENTS 3.351.556 11/1967 Tsourmas 252/103 3.434.796 3/1969 Colombo 252/103 3738,86? 6/1973 Franz 252/102 3.790.489 2/1974 Shoemaker et a1. 252/103 Primary Examiner-Benjamin R. Padgett Assismn! Examiner-Irwin Gluck Attorney, Agent. or Firm-Roger .1. Drew; Elwood J.

Schaffer [57] ABSTRACT Non-cyanide alkaline aqueous solutions for stripping non-ferrous metals, especially copper, from ferrous 1451 Jul 22, 1975 metal such as, for example, steel. The stripper solution comprises a water-soluble nitrate, a water-soluble compound of the formula wherein R represents a valence bond, {CH wherein x is an integer of l to 2,

wherein y is an integer of l to 2, or

I 220' AM and M is a compatible, hydrophilic, i.e. water-loving or water-solibilizing, cation, a water-soluble persulfate, a water-soluble urea compound, and ammonium hydroxide. Brass, cadmium and zinc can also be stripped from steel by the stripper or dissolving solutions herein.

20 Claims, No Drawings NON-CYANIDE ALKALINE COMPOSITION FOR DISSOLVING NON-FERROUS METALS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to the dissolving of nonferrous metal, and more particularly to new and improved compositions for dissolving non-ferrous metal. Additionally this invention relates to a process for the dissolution of non-ferrous metal.

2. Description of the Prior Art Stripping solutions are known in the prior art which consist of an aqueous solution of ammonium persulfate and ammonium carbonate. Although such stripping solutions are satisfactory in certain respects, they suffer from having a low capacity for copper and having a tendency to go dead" when only about 2-8 oz./gal. of copper has passed into solution and usually when about 4 oz./gal. of copper has been dissolved. By the solution going dead as the term is used herein is meant the stripping rate becomes so low that it is impractical to use the solution any further for stripping or dissolving the metal, and the solution is dumped to the sewer. Further such prior stripping solutions have a non-uniform stripping rate, and the ammonium persulfate is unstable and tends to decompose in the solution.

Nitric acid is known to be a good stripper for copper, but it is disadvantageous for stripping copper from ferrous metal, for instance steel, as the nitric acid is not selective for the copper and also attacks the steel. The nitric acid also evolves dense, noxious fumes when dissolving copper.

OBJECTS OF THE INVENTION One object of this invention is to provide new and improved solutions for dissolving or stripping non-ferrous metal, cg. copper, characterized by having a significantly higher capacity for the metal than that of the prior art dissolving or stripping solutions.

Another object of this invention is to provide new and improved solutions for dissolving or stripping nonferrous metal, e.g. copper, having a uniform and constant stripping or etch rate for the copper until the total copper capacity of the solution is reached.

A further object is to provide new and improved solutions for stripping non-ferrous meta], e.g. copper, from a ferrous metal, e.g. steel, substrate without any substantial attack on the substrate.

Still a further object of the invention is to provide new and improved stripping solutions for dissolving or stripping a non-ferrous metal characterized by being stable solutions not having a tendency to undergo premature decomposition.

An additional object is to provide non-cyanide compositions utilizable for preparing the new and improved noncyanide stripping or dissolving solutions herein.

Additional objects and advantages will be apparent as the invention is hereinafter described in more detail.

BRIEF SUMMARY OF THE INVENTION The non-cyanide alkaline solution for dissolving or stripping non-ferrous metal in accordance with this invention, in its broader aspects, comprises a watersoluble nitrate, a water-soluble compound of the formula wherein R is a valence bond, -(-CH wherein x is an integer of 1 to 2,

wherein y is an integer of 1 to 2, or

and M is a hydrophilic, i.e. water-loving or watersolubilizing, cation, a water-soluble persulfate, a watersoluble urea compound, i.e. urea per se or a urea derivative as exemplified by the derivatives of urea hereinafter disclosed, and ammonium hydroxide. Such dissolution or stripping solutions attain fully the objects hereafter set forth.

The considerably higher capacity of the dissolution or stripping solutions of the invention for copper than that of the prior art stripping solutions was a capacity of 14-18 oz./gal. of copper for the invention solutions, as contrasted with only a 2-8 oz./gal. of copper capacity reported in the prior art. This striking improvement in copper capacity provided by the stripping solutions of this invention was entirely unexpected and surpris- The combination of the water-soluble persulfate and water-soluble nitrate herein unexpectedly resulted in a pronounced synergism and a considerably more constant stripping rate, than when either such constituent was utilized in the dissolution solution and the other such constituent was omitted. Further the soluble nitrate gives the dissolution or stripping solution a considerably enhanced capacity for and tolerance to dissolved or stripped copper without going dead which was not previously enjoyed with the soluble persulfate alone in the dissolution solution. The soluble salt of the dicarboxylic acid, e.g. the water-soluble oxalate, malonate or succinate, functions to chelate the stripped or dissolved metal, for instance the stripped copper. Such salt of the dicarboxylic acid is also believed to play a secondary role in the dissolution solutions herein, which is to stabilize the water-soluble persulfate, e.g. the ammonium persulfate, by a mechanism which is presently unknown. The function of the urea or urea derivative in the dissolution solutions herein is to complex the stripped copper, to thereby hold the copper in solution. In the absence of the urea or urea derivative, the dissolution or stripping solution will tolerate or hold considerably less copper. The uncomplexed, untolerated copper tends to precipitate as an insoluble copper oxide or salt, which is undesirable. The ammonium hydroxide, in addition to its pH adjusting function, functions also to complex the stripped copper ions as a soluble complex.

The dissolution or stripping solutions herein when held in a covered container, ordinarily do not require the addition thereto of ammonium hydroxide for maintaining the pH during the stripping operation. The maintenance of the pH of the stripping solutions herein within the range of about 9-10 is important inasmuch as at much below a pH of 9, steel substrates may be attacked by the solution which usually results in a part or component which must be scrapped.

The water-soluble nitrate is usually present in the dissolution or stripper solutions of this invention in amount of about to about 85 g/l, the water-soluble compound of the formula wherein R and M have the meaning aforesaid is usually present therein in amount of about 0.1 to about g/l, the water-soluble persulfate is usually present therein in amount of about 17 to about 220 g/l, the watersoluble urea compound is usually present therein in amount of about 1 to about 65 g/l, and the ammonium hydroxide is present therein in amount sufficient to adjust the pH to within the range about 9 to about 10.

Any water-soluble nitrate that is compatible in the stripping solutions herein is utilizable in the metal dis solving or stripping solutions herein. Exemplary of the water-soluble nitrate is ammonium nitrate or an alkali metal nitrate, e.g. potassium nitrate, sodium nitrate or lithium nitrate. Likewise any water-soluble persulfate that is compatible in the stripping solutions herein is utilizable in the metal dissolving or stripping solutions herein. Exemplary of the water-soluble persulfate is ammonium persulfate or an alkali metal persulfate such as potassium persulfate. Any water-soluble urea compound, i.e. urea per se or a water-soluble derivative of urea as exemplified by the water-soluble urea deriva tives hereinafter set forth, that is compatible in the stripping solutions herein is utilizable in the stripping solutions herein.

The water-soluble urea compound is usually of the formula ps wherein R R R and R are hydrogen, lower alkyl, i.e. l4 C alkyl, phenyl, and substituted phenyl,

In the compound of the formula M can be any suitable solution-compatible hydrophilic cation. Thus M in such formula is exemplified by an ammonium cation or by an alkali metal, e.g. potassium, sodium or lithium, cation. Exemplary of such compounds are ammonium oxalate, potassium oxalate, so dium oxalate or lithium oxalate, ammonium malonate, potassium malonate, sodium malonate or lithium malonate, ammonium succinate, potassium succinate. so-

dium succinate and lithium succinate, Rochelle salt, i.e. sodium potassium tartrate, and sodium citrate.

The urea compounds herein are exemplified by urea per se, 1, l-dimethylurea', 1, 3-dimethyl-urea; l, ldiethylurea; l, 3-diethylurea; l-ethylurea, lmethylurea, lbutylurea, l, l, 3-trimethylurea; l, 3- dimethyl-l, 3-diphenylurea; l-ethyl-l-phenylurea, 1- phenylurea and l-(3-tolyl)-urea.

In another embodiment, the dissolution or stripping solutions herein may contain, as additional constituents, a water-soluble carbonate in amount up to about 45 g/l (calculated as ammonium carbonate), a watersoluble chloride in amount up to about 65 g/l (calculated as ammonium chloride), a water-soluble formate in amount up to about 25 g/l (calculated as ammonium formate), and a water-soluble citrate in amount up to about 30 g/l (calculated as ammonium citrate). Such solutions usually contain the constituents, when present therein, in proportions within the following propor- UOI] ranges:

Water-soluble nitrate (calculated as ammonium nitrate) Water-soluble compound of the formula about 20 about O l l M-O-C-RCOM wherein R and M have the meaning aforesaid (calculated as ammonium oxalate) Water-soluble carbonate (calculated as ammonium carbonate) Water-soluble persulfate (calculated as ammonium persulfate) Watersoluble chloride (calculated as ammonium chloride Water-soluble forrnate (calculated as ammonium formate) Water-soluble urea compound (calculated as urea) Water-soluble citrate (calculated as ammonium citrate) Ammonium hydroxide about 0.1 to about 20 0 to about 45 about 17 to about 220 0 to about 65 O to about 25 about 1 to about 65 0 to about 30 sufficient to adjust pH to about 9 to about 10 /l Ammonium nitrate about 20 to about 80 Compound of the formula as ammonium oxalyte about 0.1 to about 20 Ammonium carbonate 0 to about 45 Ammonium persulfate about 17 to about 220 Ammonium chloride 0 to about 65 Ammonium formate 0 to about 25 Water-soluble urea compound (calculated as urea) Ammonium citrate Ammonium hydroxide about 1 to about 65 0 to about 30 sufficient to adjust pH to about 9 to about 10 Exemplary water-soluble carbonates for use herein are ammonium carbonate and alkali metal carbonates,

e.g. sodium carbonate, potassium carbonate and lithium carbonate.

The water-soluble formates are exemplified by ammonium formate and alkali metal formates, e.g. sodium formate potassium formate and lithium formate.

The water-soluble chlorides are exemplified by ammonium chloride and alkali metal chloride, e.g. potassium chloride, sodium chloride and lithium chloride.

The water-soluble citrate is exemplified by diammonium citrate and tri-ammonium citrate and alkali metal citrates, e.g. potassium citrate, monobasic potassium citrate. sodium citrate dihydrate, sodium citrate pentahydrate, sodium citrate (2 Na C H O .l lH O), and lithium citrate.

Liquid concentrate compositions for use in preparing the metal dissolving or stripping solutions herein also are embodied in the present invention. One such concentrate composition herein comprises an aqueous solution containing the water-soluble urea compound, the water-soluble nitrate, and water and preferably also water-soluble carbonate, all of these constituents being hereinbefore disclosed. The water-soluble chloride, formate and citrate, when utilized, will usually be present in the liquid concentrate herein, although such compounds can be present, if desired, in either or both of the liquid and solid concentrate compositions herein.

Another concentrate composition of this invention for use in preparing the metal dissolving or stripping solutions is the solid concentrate composition comprising a mixture of the compound of the formula by Weight Water-soluble urea compound (calculated as urea) about 5 to about 25 Water-soluble nitrate (calculated as ammonium nitrate) Water-soluble chloride (calculated as ammonium chloride) Water-soluble formatc (calculated as ammonium formate) Water-soluble citrate (calculated as ammonium citrate) about to about 45 O to about 15 0 to about 10 0 to about 10 about 30 to about 75 In an additional embodiment of the liquid concentrate solution, the concentrate solution contains the constituents and in the proportion ranges set forth immediately supra and, as a preferred additional constituem. a water-soluble carbonate in amount of about 1 to about 5 percent by weight (calculated as ammonium carbonate) based on total concentrate solution.

The solid concentrate composition, which is ordinarily a powder concentrate, will usually contain the following constituents in proportions within the following ranges:

MOCRC-O'M wherein R and M have the meaning aforesaid (calculated as ammonium oxalate) Water-soluble chloride (calculated as ammonium chloride Water-soluble forrnate (calculated as ammonium formate) Water-soluble citrate (calculated as ammonium citrate) about 2 to about l5 0 to about 15 0 to about 10 O to about 10 In an additional embodiment of the solid concentrate composition, the solid concentrate contains the constituents and in the proportion ranges set forth immediately supra and, as a preferred additional constituent, a water-soluble carbonate in amount of about 5 to about 25 percent by weight (calculated as ammonium carbonate) based on total concentrate composition.

The liquid and solid concentrates and water are mixed together to form the ready-to-use dissolution solution in proportions usually in the ranges of about 12-39 percent of the liquid concentrate, about 3.0-9.0 percent of the solid concentrate, and about 30.0-80.0 percent of water, the percentages being by weight. NH OH is also admixed with the concentrates and water in amount sufficient to adjust the pH to within the range of about 9 to about 10.

The metal dissolving or stripping solutions herein can, if desired, be prepared by admixing the constituents in proportions within the proportion ranges disclosed herein, and without employing the liquid and solid concentrate solutions. I

The dissolving process herein involves contacting the nonferrous metal to be dissolved with the dissolving solution herein, and maintaining the metal in contact with the solution until the metal is dissolved therein. Any suitable means of contacting the non-ferrous metal with the solution is utilizable. The non-ferrous metal is usually contacted with the dissolving solution by immersing the metal therein. However, additional examples of such contacting is by pouring the dissolving solution onto the metal, or by spraying the dissolving solution onto the metal. The time of contacting the nonferrous metal, e.g. copper, with the dissolving or stripping solutions herein to dissolve it from the ferrous substrate, will vary with the temperature of the stripping solution and the amount of non-ferrous metal to be dissolved or the thickness of the non-ferrous metal deposit to be stripped. The contact time required will be less when the dissolving or stripping solution is at higher temperature, for instance elevated temperature up to about 120F., and the contact time required will be greater when the dissolving or stripping solution is at a lower temperature, for instance room temperature. A contact time of about 60 minutes was required to strip a metallic copper deposit of 1 mil thickness from a ferrous metal substrate with the stripping solution at room temperature and without agitation of the solution.

The dissolution of the non-ferrous metal in accof= dance with this invention can be effected with the di= solving solution at room temperature with good results;

Elevated temperatures of the dissolving solution herein about 30 to about can also be utilized, with solution temperatures up to about 120F. tending to speed up the dissolution of the non-ferrous metal. Although elevated solution temperatures up to about l20F. as aforementioned give good results in dissolving or stripping the metal, the life of the dissolution or stripping solution may be lowered to some extent at the elevated solution temperatures.

The process herein is eminently well suited for dissolving the non-ferrous metal as such, i.e. not on a substrate, or for selectively stripping, i.e. dissolving, the IQ non-ferrous metal from ferrous metal substrates.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred stripping solution herein contains the foll5 lowing constituents within the proportion ranges specified:

a Ammonium nitrate about 20 to about 80 Ammonium oxalate about 0.1 to about 20 Ammonium carbonate about 2 to about 45 Ammonium persulfate about 20 to about 220 Urea about I to about 50 Ammonium hydroxide sufficient to adjust the pH to about 9.5 I0

An especially preferred stripping solution herein is set forth below:

g/l Ammonium nitrate 60 Ammonium oxalate 6 Ammonium carbonate l5 Ammonium persulfate 45 Urea 30 Ammonium hydroxide 330 ml/l A preferred liquid concentrate herein contains the following constituents in proportions within the ranges hereafter set forth:

by Weight Urea per se about 10 to about 18 Ammonium nitrate about 20 to about 35 H2O about to about 60 Ammonium about 1 to about 5 carbonate Ammonium chloride 0 to about 15 Ammonium formate 0 to about 10 Ammonium citrate 0 to about l0 The powdered solid concentrate preferred herein contains the following constituents in proportions within the following ranges:

% by Weight Ammonium about 60 to about 80 persulfate Ammonium oxalate about 6 to about 13 Ammonium about 10 to about 20 carbonate Ammonium chloride 0 to about 10 Ammonium formate O to about I() The preferred liquid and solid concentrates, and water are mixed together to form the ready-to-use dissolution solution preferably in proportions within the ranges of about 16.6-20.0 percent of the liquid concentrate,

about 4.0-8.0 percent of the solid concentrate, and about 50.0 percent of water. NH OH is also admixed with the concentrates and water in amount suffi- EXAMPLE 1 EL Ammonium nitrate Ammonium oxalate 6 Ammonium carbonate Ammonium persulfate Urea Ammonium hydroxide sufficient to adjust pH to about 9.0 10.0

EXAMPLE 2 /l Potassium nitrate 40 Potassium oxalate 4 Potassium carbonate l2 Potassium persulfate 60 Urea 30 Ammonium hydroxide sufficient to adjust pH to about 9.0 10.0

EXAMPLE 3 Ammonium nitrate 40 Ammonium oxalate l0 Ammonium carbonate 45 Ammonium persulfate 45 Urea 30 Ammonium hydroxide Sufficient to adjust pH to about 9.0 10.0

EXAMPLE 4 Ammonium nitrate 60 Ammonium oxalate 8 Ammonium carbonate 45 Ammonium persulfate 45 Urea 20 Ammonium hydroxide Sufficient to adjust pH to about 9.0 l0.0

EXAMPLE 5 Ammonium nitrate 60 Ammonium oxalate 4 Ammonium carbonate 45 Ammonium persulfate 45 Ammonium chloride 5 Ammonium forrnate 20 Urea l0 Ammonium citrate 10 Ammonium hydroxide Sufficient to adjust pH to EXAMPLE 6 i Ammonium nitrate 60 Ammonium malonate 10 Ammonium carbonate 12 Ammonium persulfatc 45 Urea 30 Ammonium hydroxide Sufficient to adjust pH to about 9.0 10.0

EXAMPLE 7 Potassium nitrate 40 Potassium malonate 8 Potassium carbonate 15 Potassium persulfate 4O Urea 25 Ammonium hydroxide Sufficient to adjust pH to about 9.0 10.0

EXAMPLE 8 g/l Ammonium nitrate 60 Ammonium suceinate o Urea 30 Ammonium persulfate 45 Ammonium carbonate l2 Ammonium hydroxide Sufficient to adjust pH to about 90 10.0

EXAMPLE 9 /l Ammonium nitrate o Ammonium oxalate o Ammonium carbonate 9 Ammonium persulfate 45 Methylurea 30 Ammonium hydroxide Sufficient to adjust pH to about 9.0 10.0

EXAMPLE l0 Ammonium nitrate o0 Ammonium oxalate o Ammonium carbonate 9 Ammonium chloride Ammonium persulfate 45 Ammonium formate 2 N. N' diethylurea l0 Ammonium citrate 10 Ammonium hydroxide Sufficient to adjust pH to about 90 10.0

EXAMPLE 1 1 Ammonium nitrate so Ammonium oxalate 6 Ammonium carbonate J Ammonium persulfate 45 Methylurea l0 Ammonium hydroxide Sufficient to Ammonium carbonate 12 Ammonium persulfate 60 N. N diethylurea 10 Ammonium hydroxide Suffieient to adjust pH to about 9.0 10.0

EXAMPLE l3 Ammonium nitrate 60 Ammonium oxalate 9 Ammonium carbonate l3 Ammonium persulfate 59 Butylurea 12 Ammonium hydroxide Sufficient to adjust pH to about 9.0 10.0

EXAMPLE 14 g/l Ammonium nitrate 60 Ammonium oxalate 8 Ammonium carbonate 12 Ammonium persulfate 60 Phenylurea 4 Ammonium hydroxide Suffieient to adjust pH to about 10.0

EXAMPLE 15 /l Ammonium nitrate o0 Ammonium oxalate 6 Ammonium carbonate 9 Ammonium persulfate 45 Ethylurea 30 Ammonium hydroxide Sufficient to adjust pH to about 9.0 10.0

EXAMPLE 16 /l Ammonium nitrate 60 Ammonium oxalate .8

Ammonium carbonate 12 Ammonium persulfate 60 Methylurea 10 Ammonium hydroxide Sufficient to adjust pH to about 9.0 10.0

EXAMPLE 17 J Potassium nitrate 40 Potassium oxalate 8 Potassium carbonate 15 Potassium persulfate 45 N. N dimethylurca 10 -Continued Ammonium hydroxide Sufficient to adjust pH to about 9.0 l0.U

EXAMPLE l 8 g/l Potassium nitrate 60 l 0 Potassium malonate [0 Potassium carbonate Potassium persulfate 45 Methylurea 30 Ammonium hydroxide Sufficient to adjust pH to about 9.0 10.0

EXAMPLE 19 a. 20 Potassium nitrate so Potassium succinate h Potassium carbonate l5 Potassium persulfate 45 N. N dimethylurea 30 Ammonium carbonate Sufficicnt to adjust pH to about 9.0 l0.0

EXAMPLE 20 g/l Potassium nitrate 60 Potassium oxalate 6 Potassium carbonate 12 Potassium persulfate 60 l Phenylurea 4 Ammonium hydroxide Sufficient to adjust pH to about 9.0 A 10.0

EXAMPLE 21 a L Ammonium nitrate 60 Ammonium oxalate h Ammonium persulfate Urea 30 45 Ammonium hydroxide Suffic|ent to adjust pH to about 9.0 10.0

EXAMPLE 22 (Different proportions than Ex. 21)

g/l Ammonium nitrate 45 Ammonium oxalate b Ammonium persulfate 40 Urea 30 Ammonium hydroxide Sufficient to adjust pH to about 9.0 l0 0 EXAMPLE Z3 sfl Potassium nitrate 60 Potassium oxalate 6 Potassium persulfatc 45 ,5 Urea 25 Ammonium hydroxide Sufficicnt to adjust pH to about 9.0 A [0.0

EXAMPLE 24 Ammonium nitrate Ammonium carbonate Ammonium persulfate Ammonium oxalate Urea Ammonium hydroxide 6 30 Sufficicnt to adjust pH to about 9.0 l0.0

Sufficient to adjust pH to about 9.0 l0.0

Ammonium hydroxide The stripping solution of Example 24 stripped, i.e. dissolved. ll8 grams of copper from a steel substrate at a stripping rate of about l mil per hour at room temperature of the solution and without agitation of the solution. The stripping solution of Example 25 stripped 96.l grams of copper from a steel substrate at a stripping rate of about l mil per hour with the solution at room temperature and without agitation of the solution. In both cases, the copper was stripped without corrosive attack of the steel substrate.

What is claimed is:

1. A non-cyanide alkaline aqueous solution for dissolving nonferrous metal consisting essentially of about 15 to about 85 g/l of a water-soluble nitrate, about 0.1 to about 20 g/l of a water-soluble compound of the formula wherein R is selected from the group consisting of a valence bond, +CH wherein x is an integer of l to 2,

wherein y is an integer of l to 2, and

Q=O oM and M is a hydrophilic cation, about 17 to about 220 g/l ofa water-soluble persulfate, about 1 to about g/l of a water-soluble urea compound, and ammonium hydroxide in amount sufficient to adjust the pH to within the range of about 9 to about 10.

13 2. The solution of claim 1 also containing a watersoluble carbonate.

3. The solution of claim 1 wherein the soluble urea compound is of the formula wherein R R R and R are hydrogen, lower alkyl, phenyl or substituted phenyl.

4. The solution of claim 2 wherein the water-soluble nitrate is selected from the group consisting of nitrates of ammonium and an alkali metal, M of the compound of the formula 0 l ll is selected from the group consisting of alkali metal and ammonium cations, the water-soluble persulfate is selected from the group consisting of persulfates of ammonium and an alkali metal, and the water-soluble carbonate is selected from the group consisting of carbonates of ammonium and an alkali metal.

5. The solution of claim 4 wherein the water-soluble nitrate is ammonium nitrate, M of the formula is an ammonium cation, the water-soluble persulfate is ammonium persulfate, R R R and R of the compound of the formula are each a hydrogen atom, and the water-soluble carbonate is ammonium carbonate.

6. The solution of claim 4 also containing a watersoluble chloride. a water-soluble formate, and a watersoluble citrate.

7. The solution of claim 6 wherein the water-soluble chloride is selected from the group consisting of chlorides of ammonium and an alkali metal, and the watersoluble citrate is selected from the group consisting of citrates of ammonium and of an alkali metal.

8. The solution of claim 7 wherein the water-soluble chloride is ammonium chloride, the water-soluble formate is ammonium formate, and the water-soluble citrate is ammonium citrate.

9. A non cyanide alkaline aqueous solution for dissolving non-ferrous metal comprising the following constituents in proportions within the proportion ranges Water-soluble nitrate (calculated as ammonium nitrate) Water-soluble compound of the formula ii i MO-CRCOM wherein R is selected from the group consisting of a valence bond. -(-CH,-)-, wherein x is an about 20 to about interger of l to 2, -(-C-)- wherein y M, is an integer of l to 2, and

(\)H (I"- and M is a hydrophilic F OM cation (calculated as ammonium oxalate about 0.1 to about 20 Water-soluble carbonate (calculated Ammonium hydroxide pH to about 9 to about l0 10. The solution of claim 9 wherein the water-soluble nitrate is selected from the group consisting of nitrates of ammonium and an alkali metal, M of the formula is selected from the group consisting of ammonium and alkali metal cations, the water-soluble carbonate is selected from the group consisting of carbonates of ammonium and an alkali metal, the water-soluble persulfate is selected from the group consisting of persulfates of ammonium and an alkali metal, the water-soluble chloride is selected from the group consisting of chlorides of ammonium and an alkali metal, the watersoluble formate is selected from the group consisting of formates of ammonium and an alkali metal, and the water-soluble citrate is selected from the group consisting of citrates of ammonium and an alkali metal.

11. The solution of claim 9 wherein the water-soluble urea compound is urea.

12. The composition of claim 10 wherein the watersoluble nitrate is ammonium nitrate, R of the compound of the formula is a valence bond and M is an ammonium cation, the water-soluble carbonate is ammonium carbonate, the water-soluble persulfate is ammonium persulfate, the water-soluble chloride is ammonium chloride, the

Sufficient to adjust water-soluble formate is ammonium formate, and the water-soluble citrate is an ammonium citratev 13. A concentrate composition comprising a mixture, by weight, of about 2 percent to about 15 percent of a compound of the formula wherein R represents a valence bond. {-CH wherein x is an integer of l to 2.

wherein y is an integer of l to 2, or

and M is a hydrophilic cation (calculated as ammonium oxalate), and about 30 percent to about 90 percent of a water-soluble persulfate (calculated as ammonium persulfate 14. The concentrate of claim 13 also containing, by weight, about 5 percent to about percent ofa watersoluble carbonate (calculated as ammonium carbonate) based on total concentrate.

15. A solid concentrate composition consisting essentially of a mixture of the following constituents in proportions within the proportion ranges hereafter specified:

7! by Weight Water-soluble persulfate (calculated as ammonium persulfate Compound of the formula about to about 90 MOC-RCOM wherein R is selected from the group consisting of a valence bond, (-CH,+ wherein x is an integer of l to 2,

(-C wherein y is an integer of l to 2,

| and and M is a hydrophilic cation M 1() (calculated as ammonium oxalate about 2 to about l5 Water-soluble chloride (calculated as ammonium chloride) 0 to about l5 Water-soluble formate (calculated as ammonium formate) O to about 10 Water-soluble citrate (calculated as 5 ammonium citrate) O to about l0.

30 ranges hereafter specified:

7(- by Weight Water-soluble urea compound (calculated as urea) Water-soluble nitrate (calculated as ammonium nitrate) Water-soluble chloride (calculated about 5 to about 25 about l5 to about as ammonium chloride) 0 to about 15 Water-soluble formate (calculated as ammonium formatc) 0 to about l0 Water-soluble citrate (calculated as ammonium citrate) 0 to about 10 4O H2O about 30 to about 75 20. The concentrate of claim 19 also containing a water-soluble carbonate in amount of about 1 percent to about 5 percent by weight (calculated as ammonium carbonate) based on total concentrate. 

1. A NON-CYANIDE ALKALINE AQUEOUS SLUTION FOR DISSOLVING NON-FERROUS METAL CONSISTING ESSENTIALLY OF ABOUT 15 TO ABOUT 85 G/L OF A WATER-SOLUBLE NITRATE, ABOUT 0.1 TO ABOUT 20 G/L OF A WATER-SOLUBLE COMPOUND OF THE FORMULA
 2. The solution of claim 1 also containing a water-soluble carbonate.
 3. The solution of claim 1 wherein the soluble urea compound is of the formula
 4. The solution of claim 2 wherein the water-soluble nitrate is selected from the group consisting of nitrates of ammonium and an alkali metal, M of the compound of the formula
 5. The solution of claim 4 wherein the water-soluble nitrate is ammonium nitrate, M of the formula
 6. The solution of claim 4 also containing a water-soluble chloride, a water-soluble formate, and a water-soluble citrate.
 7. The solution of claim 6 wherein the water-soluble chloride is selected from the group consisting of chlorides of ammonium and an alkali metal, and the water-soluble citrate is selected from the group consisting of citrates of ammonium and of an alkali metal.
 8. The solution of claim 7 wherein the water-soluble chloride is ammonium chloride, the water-soluble formate is ammonium formate, and the water-soluble citrate is ammonium citrate.
 9. A non-cyanide alkaline aqueous solution for dissolving non-ferrous metal comprising the following constituents in proportions within the proportion ranges
 10. The solution of claim 9 wherein the water-soluble nitrate is selected from the group consisting of nitrates of ammonium and an alkali metal, M of the formula
 11. The solution of claim 9 wherein the water-soluble urea compound is urea.
 12. The composition of claim 10 wherein the water-soluble nitrate is ammonium nitrate, R of the compound of the formula
 13. A concentrate composition comprising a mixture, by weight, of about 2 percent to about 15 percent of a compound of the formula
 14. The concentrate of claim 13 also containing, by weight, about 5 percent to about 25 percent of a water-soluble carbonate (calculated as ammonium carbonate) based on total concentrate.
 15. A solid concentrate composition consisting essentially of a mixture of the following constituents in proportions within the proportion ranges hereafter specified:
 16. The concentrate of claim 15 also containing a water-soluble carbonate in amount of about 5 percent to about 25 percent by weight (calculated as ammonium carbonate) based on total concentrate.
 17. A liquid concentrate composition comprising an aqueous solution containing a water-soluble urea compound, a water-soluble nitrate, and water.
 18. The concentrate of claim 17 also containing a water-soluble carBonate.
 19. A liquid concentrate composition consisting essentially of an aqueous solution containing the following constituents in proportions within the proportion ranges hereafter specified:
 20. The concentrate of claim 19 also containing a water-soluble carbonate in amount of about 1 percent to about 5 percent by weight (calculated as ammonium carbonate) based on total concentrate. 